ROS2 update node parameter from client

#ros2   #param  

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Table of Content

Update parameter from other node, using set_parameters service

demo

• set my_int param from param basic node

terminal1: run node

ros2 run pkg_python_tutorial param_control

terminal2: list node params

ros2 param list
/basic_param:
  my_int
  use_sim_time

Know your environment

terminal2: list node services

ros2 service list
/basic_param/describe_parameters
/basic_param/get_parameter_types
/basic_param/get_parameters
/basic_param/list_parameters
/basic_param/set_parameters
/basic_param/set_parameters_atomically

terminal2: get service interface

# get service interface
ros2 service type /basic_param/set_parameters
#
rcl_interfaces/srv/SetParameters

terminal2: show interface details

Parameter[] parameters
    string name
    ParameterValue value
        uint8 type
        bool bool_value
        int64 integer_value
        float64 double_value
        string string_value
        byte[] byte_array_value
        bool[] bool_array_value
        int64[] integer_array_value
        float64[] double_array_value
        string[] string_array_value

---
# Indicates whether setting each parameter succeeded or not and why.
SetParametersResult[] results
    bool successful
    string reason

code

param_update_cllient.py

import rclpy
from rclpy.node import Node
from rcl_interfaces.srv import SetParameters
from rcl_interfaces.msg import Parameter, ParameterValue, ParameterType
from rcl_interfaces.srv._set_parameters import SetParameters_Response
from rcl_interfaces.msg import SetParametersResult
from rclpy.parameter_service import SetParameters

TOPIC = "/basic_param/set_parameters"

class MinimalClientAsync(Node):
    def __init__(self):
        super().__init__('update')
        self.cli = self.create_client(SetParameters, TOPIC)
        while not self.cli.wait_for_service(timeout_sec=1.0):
            self.get_logger().info('service not available, waiting again...')
        self.send_request()

    def service_call_handler(self, future):
        response: SetParameters_Response
        result: SetParametersResult
        response = future.result()
        result = response.results[0]
        self.get_logger().info(f"{result.successful}")
        self.get_logger().info(result.reason)



    def send_request(self):
        self.req = SetParameters.Request()
        param_value = ParameterValue(integer_value=150)
        param_value.type = ParameterType.PARAMETER_INTEGER
        param = Parameter(name="my_int", value=param_value)
        params = [param]
        self.req.parameters = params
        self.future = self.cli.call_async(self.req)
        self.future.add_done_callback(self.service_call_handler)

def main(args=None):
    rclpy.init(args=args)

    minimal_client = MinimalClientAsync()
    rclpy.spin(minimal_client)
    minimal_client.destroy_node()
    rclpy.shutdown()


if __name__ == "__main__":
    main()

usage

IntRange

my_int param has limit between 10-110

terminal2

# send value 150
ros2 run pkg_python_tutorial param_update
#
[INFO] [1674974296.640533953] [update]: False
[INFO] [1674974296.640736818] [update]: Parameter my_int out of range. Min: 10, Max: 110, value: 150

# send value 100
ros2 run pkg_python_tutorial param_update
[INFO] [1674974352.207990957] [update]: True
[INFO] [1674974352.208230578] [update]

reason

set_parameters service response return SetParametersResult object for each updated parameter,
the Object has two fields
- bool successful
- string reason
When update failed reason field contain the error msg